class Task63:
    def run(self, values):
        if len(values) < 2:
            return None

        min_day = 0
        max_profit = float('-inf')
        for day in range(1, len(values)):
            max_profit = max(max_profit, values[day] - values[min_day])
            if values[day] < values[min_day]:
                min_day = day

        return max_profit
